Precision aerobic irrigation reduces methane emissions in paddy fields by regulating soil redox potential and root-secreted organic acids.

The effect of water management on methane (CH) emissions from paddy has been well documented, yet the impact of Precision Aerobic Irrigation (PAI) on methanogens and methanotrophs communities, as well as their metabolic types, remain unclear. This study utilized two different irrigation regimes ((continuous flooding (CF) and PAI) to elucidate the impacts of PAI on the community structure and metabolism of methanogens and methanotrophs. The results indicated that PAI significantly reduced irrigation water use by 33.23 %, decreased CH cumulative emissions by 56.64 %, and increased rice yield by 13.06 %. Additionally, the PAI treatment enhanced the soil's redox potential (Eh) and reduced the total root-secreted organic acids (TOA). Redundancy analysis revealed significant differences in the community structures of methanogens and methanotrophs between PAI and CF treatments, which were associated with Eh, TOA, and organic acid types (P < 0.05). At the tillering stage, PAI significantly decreased the proportion of facultative methanogens while increasing acetoclastic methanogens. Structural equation modeling indicated that the metabolic types of methanogens are regulated by Eh and organic acids, with a significant positive effect on CH emission. In conclusion, our findings demonstrate that PAI reduces CH emissions from paddy fields by enhancing Eh and altering the secretion of root-derived organic acids, thereby regulating the community structure and metabolic types of methanogens and methanotrophs.